This application is a 373 of PCT International Application No. PCT/JP97/04598.
The present invention relates to a gas discharge panel and a method for manufacturing the same.
An AC type plasma display panel (hereinafter called the PDP) as shown in FIG. 7 has been known as an example of gas discharge panel.
Panel configuration and operation of the conventional PDP will be described below with reference to the accompanying drawing.
FIG. 20 is a perspective sectional view schematically showing the PDP of the prior art.
In this drawing, reference numeral 4 denotes a front substrate (also called the upper panel substrate), and 8 denotes a back substrate (also called the lower panel substrate). An outer casing 10 has such a configuration that the front substrate 4 and the back substrate 8 are disposed to oppose each other with the gap between the peripheries thereof being filled with a sealing member 9 (refer to FIG. 21) made of glass having a low melting point thereby to form a gas discharge space which is sealed to be airtight and is filled with a rare gas (a mixture of helium and xenon gases) with a pressure from 300 to 500 Torr.
The front substrate 4 comprises a front panel glass 201, display electrodes 1 formed in a pattern on the front panel glass 201, a dielectric film 2 formed to cover the display electrodes 1 and an MgO protective film 3 formed on the dielectric film 2.
The back substrate 8 comprises a back panel glass 202, address electrodes 5 (also called the data electrode) formed in a pattern on the surface of the back panel glass 202, a dielectric film 6 formed to cover the address electrodes, division walls 7 comprising a plurality of ribs, and RGB fluorescent substances 11a through 11c applied between the ribs. The division wall 7 is means for dividing the gas discharge space. Compartment 12 thus divided serve as light emitting regions, while the fluorescent substance 11 is coated separately in each of these light emitting regions. The ribs of the division walls 7 and the address electrodes 5 are formed in parallel with each other and the display electrodes 1 and the address electrodes 5 cross at right angles with each other.
In the casing 10 configured as described above, when voltages are applied to the address electrodes 5 and the display electrodes 1 at a proper timing, discharge occurs in the compartment 12 divided by the division walls 7 corresponding to display pixels so that ultraviolet rays are emitted and excite the RGB fluorescent substances 11a through 11c that in turn emit visible light which constitutes an image.
The front panel glass and the back panel glass are sealed to form a space delimited thereby that is filled with the discharge gas. Because pressure of the discharge gas filling the space is usually lower than the atmospheric pressure, however, the front panel glass and the back panel glass are pressed inward by the atmospheric pressure so that ridges of the division walls 7, or top portions of the ribs, make contact with the inner surface of the front panel glass 201, thereby keeping the clearance between the front panel glass 201 and the back panel glass 202. As a consequence, it is not necessary to bond the ridges of the division walls 7 and the inner surface of the front panel glass 201, which are merely brought into contact with each other.
Now a method for manufacturing the PDP of the prior art will be described below with reference to the accompanying drawings.
FIG. 21 is a partially cutaway perspective view schematically showing the same PDP of the prior art as shown in FIG. 20.
As shown in FIG. 21, the front substrate 4 is made by forming the electrodes 1 on the glass substrate 201, forming the dielectric film 2 to cover the electrodes 1, firing the dielectric film 2 and forming the protective film (MgO) 3 thereon by EB vapor deposition.
As for the back substrate 8, the electrodes 5 are s formed on a glass substrate 202 and is then covered the dielectric film 6 formed thereon and fired. Then after forming a layer of a material to make the division walls all over the surface by printing process, the division wall material is removed by sand blast from portions where the division wall is not to be formed thereby to form the division walls 7 in linear configuration through a firing process. Then the space between the ribs of the division walls 7 is filled with the fluorescent substance 11 by a printing process or the like, dried and fired to complete the back substrate 8.
The front substrate 4 and the back substrate 8 completed as described above are fired after applying glass of low melting point that makes the sealing member 9 to the peripheries thereof, thereby sealing the space therebetween. After evacuating the inner space through a chip tube (also called the piping member) 13, the space is filled with a rare gas and the tube is chipped off, thereby completing the PDP.
Operations of filling the inner space with the rare gas using the chip tube 13 and chipping off will be described in more detail below with reference to FIGS. 21, 22.
As shown in FIG. 21, when manufacturing the PDP (container filled with the gas) of the prior art, the lower panel substrate 8 is fitted on an external position thereof with the piping member 13 that communicates with the gas discharge space in the casing 10 via a through hole 8a formed in the lower panel substrate 8. Then after purging the air from the inside of the casing (the container before being filled with the gas) 10 and filling the inner space with the discharge gas, the piping member 13 is closed thereby sealing the inner space of the casing 10.
Closing of the piping member 13 is carried out as shown in FIG. 22(a) by heating and melting the closing portion 13a of the piping member 13 with a gas burner 14 or the like applied from the outside. After causing the piping member 13 to contract by moving the lower portion of the closing portion 13a which has melted away from the casing 10 as shown in FIG. 22(b), the piping member 13 is cut off by melting as shown in FIG. 22(c). Thus in the prior art, since the atmospheric pressure is higher than the inner pressure of the casing 10, the closing portion 13a of the piping member 13 which has contracted is completely closed due to contraction of the inner wall of the piping.
The lower panel substrate 8 bears the piping member 13, that was used when purging air from the inner space of the casing 10 and filling it with the discharge gas, remaining thereon as bonded by using the same material as the sealing member 9.
In the PDP configuration of the prior art as described above, however, the front substrate 4 and the back substrate 8 are bonded to each other on the peripheries thereof by frit glass (sealing member 9) used for sealing but mostly secured by the differential pressure between the atmospheric pressure acting thereon from the outside and the inner pressure which is below one atmosphere of the gas filing the space between the front substrate and the back substrate, that causes the front substrate to be pressed against the division walls thereby to maintain the configuration.
Pressure of the filling gas is generally from 300 Torr to 500 Torr, which is not significantly different from the atmospheric pressure of 760 Torr.
As a consequence, there has been such a problem that, when the PDP of the prior art is used onboard an airplane, for example, such a flight condition as the pressure in the airplane drops significantly below the normal atmospheric pressure causes the inner surface of the front substrate comes off the ridges of the division walls at the middle of the PDP, thus resulting in cross talk.
Even at the normal atmospheric pressure, there has been such a problem that, when the PDP is subject to vibration, the front substrate temporarily comes off the division walls thus resulting in cross talk leading to disturbed image.
Thus the PDP of the prior art configuration has problems such as the displayed image is disturbed due to vibration when used onboard vehicles such as trains and buses.
Moreover, manufacture of the PDP of the prior art involves many firing processes that require a significant number of electric furnaces, leading to high energy cost and making it difficult to achieve energy-efficient production.
The PDP of the prior art configuration has also such a problem that satisfactory brightness cannot necessarily be achieved. In order to improve the brightness, it is believed that the inner pressure of the discharge gas filing the inside of the casing 10 must be increased to a level above 500 Torr.
In the prior art configuration, however, increasing the inner pressure of the discharge gas filing the inside of the casing 10 to a level of about 760 Torr to 1000 Torr causes a gap to be generated between the ridges of the division walls 7 formed on the lower panel substrate 8 and the upper panel substrate 4, or the upper panel substrate 4 and the lower panel substrate 8 to swell outwardly.
As a consequence, there has been such a problem that isolation of the adjacent compartments 12 divided by the ribs of the division walls 7 is broken by the gap, resulting in deterioration in the quality of display by the PDP such as cross talk. Also in case the inner pressure of the discharge gas filling the inside of the casing 10 is near equal to or above the atmospheric pressure, the sealing method that makes use of the atmospheric pressure which is higher than the filling gas pressure as described in conjunction with the conventional manufacturing method can no longer be employed.
An object of the present invention is to solve the problems of the plasma display panel of the prior art described above and provide a gas discharge panel that is less prone to cross talk and is capable of producing more stable image than the prior art, and a method for manufacturing the same.
Another object of the present invention is to solve the problems of the method for manufacturing the plasma display panel of the prior art described above, and provide a method for manufacturing a gas discharge panel that is capable of reducing the number of firing processes over the prior art.
Another object of the present invention is to solve the problems of the plasma display panel of the prior art described above and provide a gas discharge panel that is capable of achieving higher brightness than the prior art, and a method for manufacturing the same.
One aspect of the present invention is a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein ridges of said division walls are bonded onto the inner surface of said first panel substrate.
Another aspect of the present invention is a gas discharge panel wherein the bonding member used in the bonding process includes a light-transmitting material.
Still another aspect of the present invention 3 is a gas discharge panel wherein the bonding member used in the bonding process includes a light-absorbing material, and the material for making said division wall includes a light-reflecting material.
Yet another aspect of the present invention is a gas discharge panel wherein the width of bonding portion between the ridge of said division wall and said first panel substrate is controlled so that the bonding portion does not intrude into a light emitting region in the divided gas discharge space.
Still yet another aspect of the present invention is a gas discharge panel wherein the bonding member used in the bonding process includes fusible glass.
A further aspect of the present invention is a gas discharge panel wherein the softening point of said bonding member is lower than the softening point of said division walls.
A still further aspect of the present invention is a gas discharge panel wherein difference in the softening point of said bonding member and said division walls is not lower than 20xc2x0 C. and not higher than 200xc2x0 C.
A yet further aspect of the present invention is a gas discharge panel wherein said division walls have holes on the ridges thereof and said bonding members infiltrates the holes.
A still yet further aspect of the present invention is a gas discharge panel wherein said division walls are formed by thermal spray process.
One aspect of the present invention is a gas discharge panel wherein at least one of the ridge surface of said division walls and portions of the inner surface of said first panel substrate bonded to the ridges has irregular shape.
Another aspect of the present invention is a gas discharge panel wherein all or a part of the ridges of said division walls are bonded onto the inner surface of said first panel substrate.
Still another aspect of the present invention is a gas discharge panel wherein said division walls are a plurality of long plate-shaped ribs disposed in parallel to each other, and the bonding is achieved by using bonding members formed linearly in a direction substantially at right angles with the longitudinal direction of said ribs.
Yet another aspect of the present invention is a gas discharge panel wherein said bonding member includes a light-absorbing material.
Still yet another aspect of the present invention is a gas discharge panel wherein notation that part of the ridges of said division walls are bonded onto the inner surface of said first panel substrate means that said bonding is provided in the vicinity of said first electrode in the ridges of said division walls.
A further aspects of the present invention is a gas discharge panel wherein the ridges of said division walls have recesses formed thereon, and said bonding is achieved by using said recesses.
A still further aspect of the present invention is a gas discharge panel wherein said division walls and said second panel substrate are bonded by using frit glass.
A yet further aspect of the present invention is a gas discharge panel wherein said gas discharge space is filled with the discharge gas with a pressure exceeding 500 Torr.
A still further aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
a process of applying bonding members, that is used for bonding the ridges of said division walls and said first panel substrate, to the ridges of said division walls or to the inner surface of said first panel substrate; and
a sealing process of forming said gas discharge space by pressurizing said first panel substrate and/or said second panel substrate that oppose each other so that a pressure is applied at least to the portions where said bonding members are provided.
One aspect of the present invention is a method for manufacturing the gas discharge panel wherein the pressurization is carried out by utilizing the resilience of a spring member.
Another aspect of the present invention is a method for manufacturing the gas discharge panel wherein the pressurization is carried out by utilizing the weight of a plate.
Still another aspect of the present invention is a method for manufacturing the gas discharge panel wherein the pressurization is carried out by interposing a shock absorber between said plate and said panel substrate
Yet another aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrode;
a second panel substrate having second electrode and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
an application process where a bonding member that is used for bonding the ridges of the division walls and said front substrate and includes fusible glass, an organic binder and an organic solvent is applied to the ridges of said division walls and/or the inner surface of said first panel substrate; and
a heating process of heating the bonding member which has been applied to a temperature not lower than the melting point of the fusible glass.
Still yet another aspect of the present invention is a method for manufacturing the gas discharge panel further comprising:
a temporary firing process provided between said application process and said heating process for heating said bonding member to such an extent as most of the organic binder and of the organic solvent included in the applied bonding member are removed; and
an assembly process provided between said temporary firing process and said heating process for assembling said first panel substrate and said second panel substrate into said gas discharge panel by means of said sealing portion.
A further aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
a division wall forming process of forming said division walls on said second panel substrate;
a bonding member arranging process where bonding members used for bonding the ridge of the division walls and the first panel substrate are disposed on said ridges, wherein
said division wall forming process comprises:
and first process of providing a mask member having a predetermined opening on said panel substrate; and
a second process of providing said division wall forming material in said opening, and the bonding member arranging process comprises:
a third process of disposing said bonding member on the ridges of said division walls formed in said second process by using said mask member; and
a fourth process of removing the mask member
A still further aspect of the present invention is a method for manufacturing the gas discharge panel wherein thermal spray method is employed in said second process and/or said third process.
A yet further aspect of the present invention is a method for manufacturing the gas discharge panel wherein said mask member includes a photosensitive material.
A still yet further aspect of the present invention is a method for manufacturing the gas discharge panel wherein said mask member is a photosensitive resin film.
One aspect of the present invention is a method for manufacturing the gas discharge panel wherein said division wall material includes fusible glass, and firing of said division walls and firing of said bonding member are carried out in the same process.
Another aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
a division wall forming process of forming said division walls on said second panel substrate;
an application process of applying fusible glass paste to the ridges of said division walls; and
a firing process of firing the fusible glass paste.
Still another aspect of the present invention is a method for manufacturing the gas discharge panel wherein said application process employs screen printing method.
Yet another aspect of the present invention is a method for manufacturing the gas discharge panel wherein a screen mask used in said screen printing method does not have a pattern.
Still yet another aspect of the present invention is a method for manufacturing the gas discharge panel wherein part of said division walls have light reflectivity and said fusible glass paste has light absorbency.
A further aspect of the present invention is a method for manufacturing the gas discharge panel wherein said firing process is a process of bonding the ridges of said division walls and the inner surface of the first panel substrate by using said fusible glass paste.
A still further aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises.:
a process of forming grooves by exposing a photosensitive material provided on said second panel substrate to light; and
a thermal spray process of filling the grooves formed in the foregoing process with a dielectric material or frit glass by thermal spray thereby to form said division walls,
while coolant gas is caused to flow along the material ejected from a thermal spray nozzle to cool down the second panel substrate in said thermal spray process.
A still further aspect of the present invention is a method for manufacturing the gas discharge panel wherein said gas discharge panel has a dielectric film that covers said second electrodes and the material making said dielectric film and said division walls is alumina.
One aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
an assembly process of assembling said first panel substrate and said second panel substrate into said gas discharge panel by means of said sealing portion;
a process of attaching a piping member, that communicates with said gas discharge space via a through hole formed in said first or second panel substrate, to the panel substrate that has the through hole;
a filling process of filling the gas discharge space with the discharge gas by using said piping member; and
a sealing process of closing said piping member while setting the pressure surrounding said piping member higher than the inner pressure of the discharge gas that fills the gas discharge space.
Another aspect of the present invention is a method for manufacturing the gas discharge panel wherein said piping member is closed by heating said piping member and pressing said piping member from the outside toward the inside so that the piping member is blocked in the sealing process.
Still another aspect of the present invention is a method for manufacturing the gas discharge panel wherein the piping member is closed by heating said piping member to melt a sealing member housed in the piping member so that the piping member is blocked in the sealing process.
Yet another aspect of the present invention is a method for manufacturing the gas discharge panel wherein the piping member is closed by surrounding said piping member with a tubular member and heating the portion of the piping member surrounded by said tubular member while pressing said piping member along the axial direction of said tubular member so that the portion of said piping member is blocked in the sealing process.
Still yet another aspect of the present invention is a method for manufacturing a gas discharge panel comprising:
a first panel substrate having first electrodes;
a second panel substrate having second electrodes and opposing said first panel substrate;
a sealing portion provided between peripheries of the two substrates for forming a gas discharge space between said first and second panel substrates; and
division walls provided on said second panel substrate for dividing said gas discharge space,
wherein the manufacturing method comprises:
a process of attaching bonding members used in bonding the ridges of said division walls and said first panel substrate to the ridges of said division walls or to the inner surface of the first panel substrate; and
a process of bonding the ridges of said division walls and said first panel substrate by means of said bonding members.